Vehicle power storage controller

ABSTRACT

A rotary electric machine ( 1 ) which constitutes a prime bar of a vehicle and an electricity storage device ( 10 ) serving as a main power source of the rotary electric machine ( 1 ) and composed of a plurality of capacitor modules ( 11 ) in which a plurality of capacitor cells make one set are provided. A hybrid control unit ( 3 ) which comprises a means for calculating assigned voltages of the capacitor modules, a means for calculating an average value of the assigned voltages of the capacitor module, and a means for equalizing the assigned voltages of the capacitor modules based on the average value. By restricting a difference among the assigned voltages of the capacitor modules ( 11 ), it is possible to fully utilize a capacity of the electricity storage device ( 10 ).

TECHNICAL FIELD

The present invention relates to an electricity storage controller forvehicles in which a prime bar is equipped with a rotary electricmachine.

BACKGROUND ART

A technology of applying an electric double layer capacitor, in whichquick charge is possible and a charge-and-discharge cycle life is long,as an electricity storage device for an electric motor coach, such as ahybrid vehicle, has attracted attention.

In order to constitute an electricity storage device having a requiredcapacity, each capacitor module is formed by connecting a plurality ofcapacitor cells in series and a plurality of the capacitor modules areconnected with each other in a row or in series.

In JP06-343225A which is a Japanese Patent Laid-Open Publication, anelectricity storage device in which in order to adjust assigned voltagesof such capacitors, a terminal voltage of each capacitor is comparedwith a stipulated voltage previously set and when the terminal voltagereaches the stipulated voltage, a bypass circuit for bypassing thecapacitor is closed so as to avoid a further charge is disclosed, and itis well known.

In this case, however, when the speed of a vehicle is reduced or thelike, energy is regenerated, more specifically, a rotary electricmachine is caused to generate electricity as an electric generator andthe capacitor is charged with the electric power generated. Then, if theelectric power regenerated is little, there will sometimes be the casethat a difference of the voltages among the capacitors is not solvedindefinitely.

In this case, it is required to periodically carry out chargingprocesses in which the assigned voltages of a capacitor cell areequalized (initialized) with a limit value. Also, external chargingequipment is required and charging time is required before the vehicleis driven. This is a disadvantage which can be anticipated.

The present invention is directed to solve such problems.

More specifically, an advantage of the present invention is to restraina difference of assigned voltages among respective capacitors bycontrolling charge and discharge of the capacitors based on an averagevalue of the voltages among the capacitors.

DISCLOSURE OF THE INVENTION

An electricity storage controller for vehicles according to the presentinvention comprises, a rotary electric machine which constitutes a primemover of a vehicle, an electricity storage device serving as a mainpower source of the rotary electric machine and composed of a pluralityof capacitor modules in which a plurality of capacitor cells, a meansfor calculating assigned voltages each of the capacitor module, a meansfor calculating an average value of the assigned voltages of thecapacitor modules, and a means for equalizing the assigned voltages ofthe capacitor modules based on the average value.

Therefore, according to the present invention, assigned voltages inunits of the capacitor modules are calculated, an average voltage ofthese assigned voltages is calculated from these, and a difference amongthe assigned voltages of the capacitor modules is modified byequalization based on the average voltage. Thus, electricity is equallystored in the capacitor modules as much as possible whether the voltagesare high or low, it is possible to cause all the capacitors to equallyfunction, and the capacity (storage capacity) of the electricity storagedevice can fully be utilized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system showing an embodiment of thepresent invention.

FIG. 2 is a block diagram of a capacitor module similarly.

FIG. 3 is a functional block diagram showing bypass processingsimilarly.

FIG. 4 is a flowchart showing the contents of control by a hybrid ECUsimilarly.

FIG. 5 is a pattern diagram of a communication system.

BEST MODE FOR CARRYING OUT THE INVENTION

In FIG. 1, reference numeral 1 represents a rotary electric machine(motor generator) which constitutes a prime bar of a vehicle, and apermanent magnet type synchronous motor (IPM synchronous motor) isadopted in consideration of high efficiency, miniaturization, and weightsaving. Reference numeral 10 represents an electricity storage device,and the rotary electric machine 1 is connected with the electricitystorage device 10 via an inverter 2.

In response to a demand of a hybrid ECU 3, the inverter 2 controls therotary electric machine 1 to be in an electromotive (driving) mode or ina power generation mode. In the electromotive mode, storage electricpower (direct-current electric power) of the electricity storage device10 is converted into alternate-current electric power, and thealternate-current electric power is supplied to the rotary electricmachine 1 so as to drive the rotary electric machine 1. On the otherhand, in the power generation mode, electric power (alternate-currentelectric power) generated by the rotary electric machine 1 is convertedinto direct-current electric power so as to charge the electricitystorage device 10.

The electricity storage device 10 constitutes a power source of therotary electric machine 1 and comprises a plurality of capacitor modules11 (MDL1-MDLm) which are connected in series, a main circuit breakconductor (relay circuit) 14, a main circuit fuse 15, a total voltagedetecting amplifier 16, a main circuit power source line (+) 17, and amain circuit power source line (−) 18.

The capacitor module 11 is composed of a plurality of capacitor cells 30which are connected in series and a control circuit board 40 forcontrolling quantity of these storage electricity. The plurality ofcapacitor modules 11 and the plurality of capacitor cells 30 are notrestricted to the series connection shown in the drawing. It isjustifiable that parallel connection is used together with the seriesconnection (see FIG. 5).

The main circuit break conductor 14 closes a main circuit from theplurality of the capacitor modules 11 to the inverter 2 when coils areexcited. On the other hand, the main circuit break conductor 14 opensthe main circuit when the coils are demagnetized. The total voltagedetecting amplifier 16 detects, in a state of insulation from the maincircuit, voltages which extend over both ends of the plurality ofcapacitor modules 11. The detection signal is outputted to the hybridECU 3.

Reference numeral 4 represents an electrical installation system powersource (battery). The electrical installation system power source closesthe main circuit break conductor 14 by putting a key switch 5 andsupplies electric power to respective electrical components (includingthe hybrid ECU 3, the inverter 2, and the control circuit board 40).

The hybrid ECU 3 controls the entire system. In order to exchange allkinds of information (detection data, control commands, and the like)between the hybrid ECU 3 and the inverter 2 of the rotary electricmachine 1 and between the hybrid ECU 3 and the control circuit board 40of each module 11, a communication network 21 (CAN communication) isformed. Reference numeral 22 represents terminal resistance of thecommunication network 21.

Additionally, in FIG. 5, reference numeral 2 la represents a main lineof the CAN communication, and each control circuit board 40 of therespective modules 11 is connected with the main line 2 la via a branchline 21 b in such a manner that the control circuit board 40 issuspended from the main line 21 a. The control circuit board 40exchanges all kinds of information in units of module with the hybridECU 3. In FIG. 5, with respect to the plurality of capacitor modules 11,four modules (MDL1˜MDL4) are connected with the min circuit in series orin a row.

The control circuit board 40 is constituted as shown in FIG. 2. A bypasscircuit 50 is composed of current-limit resistance 41 and a transistor42, and the bypass circuit 50 is connected with a capacitor cell 30 in arow every capacitor cells which are connected in series (C1˜Cn). Basedon an output of a comparator 44 and an output of a bypass switchingcircuit 49, an OR circuit 43 outputs an ON (bypass actuation) signal tothe transistor 42 when either of the outputs becomes a high level signal(bypass command). The transistor 42 closes the bypass circuit 50 whenbase voltage is applied due to an ON signal from the OR circuit 43. Onthe other hand, the transistor 42 opens the bypass circuit 50 when theapplication of base voltage is released due to an OFF signal of the ORcircuit 43.

The comparator 44 outputs a bypass command for initializing theelectricity storage device to maximum voltage. The comparator 44compares an assigned voltage of the capacitor cell 30 with a thresholdvoltage which corresponds to the maximum voltage of the electricitystorage device 3 and is set by a voltage generator 45. Then thecomparator 44 outputs a bypass command to the OR circuit 43 of thecapacitor cell 30 in which the assigned voltage exceeds the thresholdvoltage.

Further, the bypass switching circuit 49 outputs a bypass command to theOR circuit 43 of the capacitor cell 30 (C1˜Cn) which requires bypassingin order to modify (equalization) a difference among assigned voltagesof the capacitor cell 30.

A voltage detection switching circuit 46 detects the assigned voltages(cell voltages) of the capacitor cell 30 one after another. Thedetection signal is insulated from a main circuit system power source byan insulation amplifier and is outputted to a CPU 53 via an AD converter47. The CPU 53 exchanges necessary information with the hybrid ECU 3 viaa communication circuit 52. At the same time, while using control datastored in a RAM 54, the CPU 53 carries out bypass processing forequalization (alignment) of assigned voltages in units of cell based onprograms stored in a ROM 55 and also controls the execution of thebypass processing for alignment of assigned voltages in units of modulein response to a demand of the hybrid ECU 3.

Reference numeral 51 represents an output circuit which outputs a cellswitching signal for proceeding the changeover of bypass targets oneafter another to the bypass switching circuit 49 according to a commandfrom the CPU 53. Similarly, the output circuit outputs a cell switchingsignal for proceeding detection of voltage one after another to thevoltage detection switching circuit 46 according to a command from theCPU 53.

In the CPU 53, assigned voltages of the capacitor cell 30 are read outone after another and a difference ΔV between a maximum voltage Vmax anda minimum voltage of these assigned voltages is found. When thedifference ΔV (dispersion) becomes a prescribed value Vk or more, thebypass processing for alignment of the assigned voltages in units ofcell will be carried out based on the information from the hybrid ECU 3if the electricity storage device 10 is in a state of being charged, thecharging current is at a stipulated value or less, and a moduletemperature does not exceed a normal range.

Assigned voltages of the capacitor cells 30 (C1˜Cn) are summed up, atotal voltage Vt of each capacitor module is found, and the totalvoltage Vt is divided by the number n of the capacitor cells, whereby anaverage voltage Vmean of the capacitor cells 30 is found. Then, a bypassreference voltage (Va=Vmean+Vk/2) is set based on the average voltageVmean. A bypass command is outputted to the OR circuit 43 of thecapacitor cell 30 in which the assigned voltage is Va or more among fromthe capacitor cells 30 (C1˜Cn).

Because a part of charging currents to be charged to the capacitor cellin which the assigned voltage is Va or more flows through the bypasscircuit 50, a difference among the assigned voltage in units of cell isdecreased with the progress of charging time.

Information is taken into the hybrid ECU 3 from the capacitor modules 11(MDL1˜MDLm). With respect to each capacitor module 11, the assignedvoltages of the capacitor cells 30 are read out and the assignedvoltages of each capacitor cell 30 are summed up as a total voltage ofeach module (module total voltage). By dividing a combined value of thetotal voltage by the number m of modules, an average voltage in units ofmodule (module average voltage) is found. The average voltage and thetotal voltage of each module 11 (MDL1˜MDLm) are compared and a voltagealignment demand flag=1 is set for the capacitor module 11 which carriesa module average voltage or less.

When a state of a vehicle is detected, there is a capacitor module towhich a voltage alignment demand flag=1 is set, and the state of thevehicle allows bypass processing, an average voltage Vmean′ in units ofcell is found from an average voltage in units of module and a bypassreference voltage (Vmean′+Offset) is set based on the average voltageVmean′ in units of cell. Bypass processing with the bypass referencevoltage (Vmean′+Offset) is required of the CPU 53 of the capacitormodule 11 to which the voltage alignment demand flag=1 is set.

This demand will have priority over bypass processing in units of cellin the CPU 53 unless a module temperature exceeds a normal range. Insuch a state of a vehicle that charge and discharge do not take placebetween the electricity storage device 10 and the rotary electricmachine (when an inverter current is zero), a part of the storagecurrents of the capacitor cell 30 in which the assigned voltages exceedthe bypass reference voltage (Vmean′+Offset) flows out of the capacitorcell 30 and flows through the bypass circuit 50. Due to conversion intothermal energy, the assigned voltage of the relevant capacitor cell 30drops. At the time of electric charge with a constant current, a part ofthe charging currents of the capacitor cell 30 in which the assignedvoltages exceed the bypass reference voltage (Vmean′+Offset) flowsthrough the bypass circuit 50. Thus, rise of the assigned voltages ofthe relevant capacitor cell 30 is restricted and a difference among theassigned voltages in units of module is decreased.

FIG. 3 shows a functional block diagram of the hybrid ECU 3 and the CPU53 of each capacitor module 11 (module CPU) which relates to bypassprocessing for alignment of the assigned voltages in units of module.

A means a (cell voltage detecting means) for reading out the assignedvoltages (cell voltages) of the capacitor cell 30 one after another, ameans b (module circuit board temperature detecting means) for readingout a temperature (detection signal of a temperature sensor not shown inthe drawing) of the control circuit board 40 as a module temperature, ameans c (cell temperature detecting means) for reading out a temperature(detection signal of the temperature sensor not shown in the drawing) ofthe capacitor cell 30 similarly, a means d (module total voltagecalculating means) for finding a total voltage of the relevant module 11based on detected data of the cell voltage, a means e (moduleabnormality detecting means) for determining from detected data of amodule temperature (circuit board temperature, cell temperature) whetheror not an inner temperature of the relevant module 11 is within a normalrange, a cell voltage alignment determining means f, and a cell voltagealignment means g are provided in the module CPU 53.

The cell voltage alignment determining means f determines whether or notthe bypass processing is allowed and whether or not the bypassprocessing is required. When the bypass processing is required andallowed, the cell voltage alignment means g outputs a bypass command tothe capacitor cell 30 in which the assigned voltages (cell voltages)exceed the bypass reference voltage in the process of proceeding thebypass processing of the capacitor cell 30 one after another. In case ofthe bypass processing for alignment of the assigned voltages in units ofcell, the bypass reference voltage is set at (Vmean+Vk/2). On the otherhand, in case of the bypass processing for alignment of the assignedvoltages in units of module, the bypass reference voltage is set at(Vmean+Offset).

The hybrid ECU 3 comprises, a means (h) (vehicle condition signaldetecting means) for reading out a detection signal (vehicle speedsignal, motor rotation signal, inverter current signal, or the like) ofall kinds of sensors, switches, and the like which are not shown in thedrawing, a means (i) (charge-and-discharge state determining means) fordetermining a charge-and-discharge state from these detection data, ameans (6) (capacitor module information detecting means) for taking indetection data (cell voltage, circuit board temperature, celltemperature) and information (results of determination of alignment orthe like) from the module CPU 53, a module average voltage calculatingmeans (k), a module space alignment demand means (p), a cell averagevoltage calculating means (q), and a demand cell voltage calculatingmeans (r).

An ID number of each module 11 is attached to detection data orinformation from the module CPU 53 and the detection data or theinformation is transmitted to the hybrid ECU 3. In the module averagevoltage calculating means k, assigned voltages of the capacitor cells 30are summed up every modules as the total voltages of the capacitormodules 11 and the average voltage in units of module is found bydividing a combined value of the total voltages by the number m of themodules.

When the average voltage in units of module and the total voltage(module total voltage) of each module 11 are compared one after anotherand the charge-and-discharge state and the module temperature meet thecriterion for permitting the capacitor module 11 in which the moduletotal voltage is the module average voltage or less to carry out thebypass processing (a vehicle condition in which charge and discharge donot take place between the electricity storage device 10 and the rotaryelectric machine and a state of electric charge with a constantcurrent), the module space alignment demand means (p) generates a demandfor bypass processing.

The cell average voltage calculating means converts an average voltagein units of module into an average voltage (cell average voltage) inunits of cell by dividing the average voltage in units of module by thenumber n of cells. When the demand cell voltage calculating meansreceives a demand for bypass processing, the demand cell voltagecalculating means calculates a bypass reference voltage (Vmean′+Offset)based on the cell average voltage and transmits to the capacitor module11 in which the module total voltage is the module average voltage orless.

FIG. 4 is a flowchart showing the contents of control by the hybrid ECU3 which relate to bypass processing for alignment of the assignedvoltages in units of module. At the first step S1, a cell voltage ofeach capacitor module 11 is read out. At the second step S2, cellvoltages are summed up every modules. At the third step S3, total valuesof the cell voltages in the respective modules 11 are added together andthe combined value is divided by the number m of modules so as to findthe module average voltage.

At the fourth step S4 and the fifth step S5, the module average voltageand the total value (module total voltage) of the cell voltages everymodules 11 are compared and it is determined whether or not the moduleaverage voltage is less than the module total voltage. If thedetermination at S5 is affirmative, at S6 the voltage alignment demandflag=1 will be set to the capacitor module 11 in which the moduleaverage voltage is less than the module total voltage. On the otherhand, if the determination at S5 is negative, the voltage alignmentdemand flag=0 will be set to the capacitor module 11 in which the moduleaverage voltage is equal to or greater than the module total voltage atthe fourteenth step S14.

At the seventh step S7, it is determined whether or not there is anycapacitor modules 11 to which the voltage alignment demand flag=1 isset. If the determination at S7 is affirmative, the step will advance tothe eighth step S8. On the other hand, if the determination at S7 isnegative, the step will escape to RETURN. At eighth step S8 and ninthstep S9, a vehicle condition signal is read out and it is determinedwhether or not the vehicle condition (charge-and-discharge state)including the module temperature is in a stable condition which meets acriterion for permitting the bypass processing. If the determination atS9 is negative, the step will return to S8. On the other hand, if thedetermination at S9 is affirmative, the step will advance to the tenthstep S10.

At S10, “cell average voltage=module average voltage/number of cells” iscalculated from the module average voltage. At the eleventh step S11,the bypass reference voltage (Va=Vmean′+Offset) for alignment of theassigned voltages in units of module is calculated. At the twelfth stepS12, it is determined whether or not there are any capacitor cells 30 inwhich the cell voltage is greater than the bypass reference voltage inthe capacitor module 11 to which the voltage alignment demand flag=1 isset. If the determination at S12 is negative, the step will escape toRETURN. On the other hand, if the determination at S12 is affirmative,the capacitor module 11 to which the voltage alignment demand flag=1 isset will be demanded to output a bypass command to the capacitor cell 30in which the cell voltage is greater than (Vmean′+Offset) at thethirteenth step S13.

Based on such constitution, a difference among the assigned voltages inunits of module is favorably modified due to the bypass processing foralignment of the assigned voltages in units of module. Thus, also in anexchange of modules, alignment of the assigned voltages in units ofmodule between a new product and an existing product is efficientlyperformed.

In this embodiment, by jointly using the bypass processing for alignmentof the assigned voltages in units of module and the bypass processingfor alignment of the assigned voltages in units of cell, it is possibleto accurately align the assigned voltages of the capacitor cells 30 inthe entire power source. Thus, when the maximum voltage (corresponds tothe threshold voltage of a generator) of the electricity storage device10 is set, it is possible to reduce a margin to be added inconsideration of a difference among the assigned voltages in units ofcell and a difference among the assigned voltages in units of module,and therefore the capacity of the electricity storage device 10 canfully be utilized.

The present invention is not restricted to the embodiment describedabove and includes various improvement and modification which can bemade by a person skilled in the art based on the contents given in theclaims.

INDUSTRIAL APPLICABILITY

The electricity storage controller for vehicles according to the presentinvention can be applied for a vehicle having a motor as a prime bar,such as a truck and a car.

1. An electricity storage controller for vehicles comprising: a rotaryelectric machine which constitutes a prime mover of a vehicle; anelectricity storage device serving as a main power source of the rotaryelectric machine and composed of a plurality of capacitor modules eachof which contains plural capacitor cells; means for calculating assignedvoltages of each capacitor modules; means for calculating an averagevalue of the assigned voltages; and means for equalizing the assignedvoltages of each modules based on the average value.
 2. An electricitystorage controller for vehicles according to claim 1, wherein the meansfor equalizing the assigned voltages of modules based on the averagevalue comprising: bypass circuits, which are normally open, areconnected in parallel, respectively, with each capacitor cells that areconnected in series; means for calculating an average value of assignedvoltages of the capacitor cells from the average value of the assignedvoltages of the capacitor modules; means for setting a bypass referencevoltage based on the average value of the assigned voltages of thecapacitor cells; and means for closing the bypass circuit of thecapacitor cell, in which the assigned voltage of the capacitor cellexceed the bypass reference voltage, of the capacitor module in whichthe assigned voltage of the capacitor module exceed the average value ofthe capacitor module.
 3. An electricity storage controller for vehiclesaccording to claim 1, further comprising means for determining whetheror not vehicle conditions allow closing of the bypass circuit, thebypass circuit can be closed only when the determination means makesaffirmative determination.
 4. An electricity storage controller forvehicles according to claim 3, wherein the determination means does notallow the affirmative determination when a temperature of the capacitormodule exceeds a normal range.
 5. An electricity storage controller forvehicles according to claim 3, wherein the determination means does notallow the affirmative determination when an inverter current of aninverter which is a relay between the rotary electric machine and theelectricity storage device is greater than a stipulated value.
 6. Anelectricity storage controller for vehicles according to claim 2,wherein the bypass circuit comprises a resistance and a bypasstransistor.
 7. An electricity storage controller for vehicles accordingto claim 2, wherein the means for calculating assigned voltages of thecapacitor modules comprises means for detecting assigned voltages ofeach capacitor cells which are connected in series and means for summingup detected values of the assigned voltages of the capacitor cells as atotal voltage of each capacitor module.
 8. An electricity storagecontroller for vehicles according to claim 7, wherein the means forcalculating an average value of assigned voltages of the capacitormodules comprises means for summing up a total voltage of each capacitormodules and means for dividing its total value by number of capacitormodules.
 9. An electricity storage controller for vehicles according toclaim 2, wherein the means for calculating an average value of assignedvoltages of the capacitor cells from the average value of the assignedvoltages of the capacitor modules is means for dividing an average valueof assigned voltages of the capacitor modules by number of series of thecapacitor cells of a set of the capacitor modules.
 10. An electricitystorage controller for vehicles according to claim 2, further comprisingmeans for determining whether or not vehicle conditions allow closing ofthe bypass circuit, the bypass circuit can be closed only when thedetermination means makes affirmative determination.